4-amino Biphenyl (4-ABP) is an aromatic amine (arylamine). 4-ABP can be found as a constituent of tobacco smoke, in the form of an environmental carcinogen. It is metabolized by hepatic cytochrome P4501A2 to yield a direct-acting mutagen known as N-hydroxy-aminobiphenyl. Yet, the accumulation of biologically active metabolites is dependent on the activation and detoxification of N-acetylation. 4-ABP has been shown to be a bladder carcinogen in humans and rodents. As well as genetic factors, 4-ABP may also play a role in breast cancer. It is hypothesized that smokers may have higher levels of DNA adducts than non-smokers and that the role of 4-ABP-DNA adducts and their relationship to tobacco exposure may be related to breast tumorigenesis. The antibody has been used to investigate the role of 4-ABP in the study of human breast cancer by measuring 4-ABP-DNA adducts.